The United Nations estimates the total possibility of ocean energy at 15 trillion kilowatt-hours, of which "roughly 15 percent has been developed so far," according to a report by Pike Research, which forecasts marine renewables as globally capturing 25 gigawatts by 2025.

The report covered tidal stream turbines, wave energy, river hydrokinetic, ocean current and ocean thermal. If effective carbon regulations and targets were in place by 2025, marine renewable and river hydrokinetic technologies could provide potentially 200 gigawatts, eight times the currently expected 25.

If that was to be the case, the sizeable majority of power is expected to come from wave energy (115 GW) followed by tidal streams (57 GW) and tidal barrage (20 GW) systems. Ocean thermal (1 GW) follows in last, after ocean current (4 GW) and river hydrokinetic (3 GW).

A marine renewable energy advocate interviewed by Pike Research said that the capital costs of marine reneable energy systems will be "50 to 100 times smaller than investments required to create the same amount of electricity from either wind or solar." Marine kinetics are able to avoid the high capital cost of other renewable energy technologies; that is to say, the popular renewable caveat of initial price barriers could be less challenging with ocean power.

Wave power is forecasted to develop at the highest rate, followed by tidal barrages, which are effectively dams and have been thought to lead to a greater risk of ecological impact. The report also highlights that the Electric Power Research Institute has disputed the perception that global hydropower resources are currently maximized, and could generate 85,000 to 95,000 more megawatts with expansion to 23,000 megawatts by 2025.

Ocean power is also receiving attention in Oregon, as they are soon to explore hydrokinetic options. Advanced Research Corporation recently received a contract with the Oregon Wave Energy Trust to perform a coastal wave energy infrastructure assessment.

The assessment will identify wave energy infrastructure needs and planning in a report scheduled for release this December. The assessment from the Newport-based corporation is intended to "inform and guide Oregon and wave energy developers as we work to continue… development," according to Kevin Banister, president of the board of directors at the Oregon Wave Energy Trust.

At the diagonally opposite end of the country, research at Florida Atlantic University, is beginning to explore the possibilities of utilizing the strongest current in the world, the Gulf Stream. Sea turbines may very well be powering the fourth largest state, which is already facing an energy crisis, according to the director of Florida Atlantic University's Center of Excellence in Ocean Energy Technology, Frederick Driscoll.

Scientists say that the energy collected from the Gulf Stream's current could generate anywhere from four to 10 gigawatts of power, said Sue Skemp, executive director at FAU's Center of Ocen Energy Technology, "the equivalent of four to ten nuclear power plants."

Underwater turbines are similar to wind turbines, but questions remain unanswered, such as what impacts on the local marine environment will be and what the actual costs of implementation would total.

Earlier this year, Doppler current profilers were released into the Atlantic, revealing to researchers how much energy can be safely extracted to meet the vision of the pilot program of developing a 20-kilowatt turbine by early 2010. So far, Florida has allocated over $13 million in grants towards research and development of the pilot project, which if successful would take another five to 10 years until completed.

Marine renewable research and development could face change by some new priorities by the Obama administration, cutting the proposed $40 million dedicated to the sector by 25-percent, possibly testing the resilience of some startups.

The future for ocean energy is not guaranteed to be rosy, but is receiving positive support, faced by the same issue that many renewables confront— unknown deployment and maintenance costs.

Photo of Swedish hydropower plant courtesy of Flickr.